An ectopic pregnancy occurs when a fertilized egg implants somewhere other than the main cavity of the uterus. Pregnancy begins with a fertilized egg. Normally, the fertilized egg attaches itself to the lining of the uterus.

An ectopic pregnancy most often occurs in one of the tubes that carry eggs from the ovaries to the uterus (fallopian tubes). This type of ectopic pregnancy is known as a tubal pregnancy. In some cases, however, an ectopic pregnancy occurs in the abdominal cavity, ovary or neck of the uterus (cervix).

Early treatment of an ectopic pregnancy can help preserve the chance for future healthy pregnancies.

At first, an ectopic pregnancy might not cause any signs or symptoms. In other cases, early signs and symptoms of an ectopic pregnancy might be the same as those of any pregnancy — a missed period, breast tenderness and nausea.

If you take a pregnancy test, the result will be positive. Still, an ectopic pregnancy can't continue as normal.

Light vaginal bleeding with abdominal or pelvic pain is often the first warning sign of an ectopic pregnancy. If blood leaks from the fallopian tube, it's also possible to feel shoulder pain or an urge to have a bowel movement — depending on where the blood pools or which nerves are irritated. If the fallopian tube ruptures, heavy bleeding inside the abdomen is likely — followed by lightheadedness, fainting and shock.

When to see a doctor

Seek emergency medical help if you experience any signs or symptoms of an ectopic pregnancy, including:

Severe abdominal or pelvic pain accompanied by vaginal bleeding

Extreme lightheadedness or fainting

Shoulder pain

A tubal pregnancy — the most common type of ectopic pregnancy — happens when a fertilized egg gets stuck on its way to the uterus, often because the fallopian tube is damaged by inflammation or is misshapen. Hormonal imbalances or abnormal development of the fertilized egg also might play a role.

Up to an estimated 20 in every 1,000 pregnancies are ectopic. Various factors are associated with ectopic pregnancy, including:

Previous ectopic pregnancy. If you've had one ectopic pregnancy, you're more likely to have another.

Inflammation or infection. Inflammation of the fallopian tube (salpingitis) or an infection of the uterus, fallopian tubes or ovaries (pelvic inflammatory disease) increases the risk of ectopic pregnancy. Often, these infections are caused by gonorrhea or chlamydia.

Fertility issues. Some research suggests an association between difficulties with fertility — as well as use of fertility drugs — and ectopic pregnancy.

Structural concerns. An ectopic pregnancy is more likely if you have an unusually shaped fallopian tube or the fallopian tube was damaged, possibly during surgery. Even surgery to reconstruct the fallopian tube can increase the risk of ectopic pregnancy.

Contraceptive choice. Pregnancy when using an intrauterine device (IUD) is rare. If pregnancy occurs, however, it's more likely to be ectopic. The same goes for pregnancy after tubal ligation — a permanent method of birth control commonly known as "having your tubes tied." Although pregnancy after tubal ligation is rare, if it happens, it's more likely to be ectopic.

Smoking. Cigarette smoking just before you get pregnant can increase the risk of an ectopic pregnancy. And the more you smoke, the greater the risk.

When you have an ectopic pregnancy, the stakes are high. Without treatment, a ruptured fallopian tube could lead to life-threatening bleeding.

Seek emergency medical help if you develop any signs or symptoms of an ectopic pregnancy, including:

Severe abdominal or pelvic pain accompanied by vaginal bleeding

Extreme lightheadedness or fainting

If you have possible signs or symptoms of an ectopic pregnancy — such as light vaginal bleeding or abdominal pain — contact your doctor. He or she might recommend an office visit or immediate medical care.

Here's some information to help you prepare, as well as what to expect from your doctor.

What you can do

Ask a loved one or friend to be with you, if possible. Sometimes it can be difficult to remember all of the information provided, especially in an emergency situation. If you can, it's also helpful to jot down your questions ahead of time. Here are some basic questions you might want to ask your doctor:

What kinds of tests do I need?

If the pregnancy isn't located in my uterus, where is it?

What are the treatment options?

What are my chances of having a healthy pregnancy in the future?

How long should I wait before trying to become pregnant again?

Will I need to follow any special precautions if I become pregnant again?

Have you had any reproductive surgery, including any that involved your fallopian tubes?

Have you been diagnosed with any sexually transmitted infections?

Have you had in vitro fertilization?

What form of birth control do you use, if any?

Do you plan to become pregnant in the future?

Are you being treated for any other medical conditions?

Are you taking any medications?

If your doctor suspects an ectopic pregnancy, he or she might do a pelvic exam to check for pain, tenderness, or a mass in the fallopian tube or ovary. A physical exam alone usually isn't enough to diagnose an ectopic pregnancy, however. The diagnosis is typically confirmed with blood tests and imaging studies, such as an ultrasound.

With a standard ultrasound, high-frequency sound waves are directed at the tissues in the abdominal area. During early pregnancy, however, the uterus and fallopian tubes are closer to the vagina than to the abdominal surface. The ultrasound will likely be done using a wandlike device placed in your vagina (transvaginal ultrasound).

Sometimes it's too soon to detect a pregnancy through ultrasound. If the diagnosis is in question, your doctor might monitor your condition with blood tests until the ectopic pregnancy can be confirmed or ruled out through ultrasound — usually by four to five weeks after conception.

In an emergency situation — if you're bleeding heavily, for example — an ectopic pregnancy might be diagnosed and treated surgically.

A fertilized egg can't develop normally outside the uterus. To prevent life-threatening complications, the ectopic tissue needs to be removed.

If the ectopic pregnancy is detected early, an injection of the drug methotrexate is sometimes used to stop cell growth and dissolve existing cells. It's imperative that the diagnosis of ectopic pregnancy is certain before this treatment is undertaken.

After the injection, your doctor will monitor your blood for the pregnancy hormone human chorionic gonadotropin (HCG). If the HCG level remains high, you might need another injection of methotrexate.

In other cases, ectopic pregnancy is usually treated with laparoscopic surgery. In this procedure, a small incision is made in the abdomen, near or in the navel. Then your doctor uses a thin tube equipped with a camera lens and light (laparoscope) to view the area.

Other instruments can be inserted into the tube or through other small incisions to remove the ectopic tissue and repair the fallopian tube. If the fallopian tube is significantly damaged, it might need to be removed.

If the ectopic pregnancy is causing heavy bleeding or the fallopian tube has ruptured, you might need emergency surgery through an abdominal incision (laparotomy). In some cases, the fallopian tube can be repaired. Typically, however, a ruptured tube must be removed.

Your doctor will monitor your HCG levels after surgery to be sure all of the ectopic tissue was removed. If HCG levels don't come down quickly, an injection of methotrexate may be needed.

You can't prevent an ectopic pregnancy, but you can decrease certain risk factors. For example, limit your number of sexual partners and use a condom when you have sex to help prevent sexually transmitted infections and reduce the risk of pelvic inflammatory disease. Quitting smoking before you attempt to get pregnant may also reduce your risk.

Losing a pregnancy is devastating, even if you've only known about it for a short time. Recognize the loss, and give yourself time to grieve. Talk about your feelings and allow yourself to experience them fully.

Rely on your partner, loved ones and friends for support. You might also seek the help of a support group, grief counselor or other mental health provider.

Most women who have ectopic pregnancies go on to have other, healthy pregnancies. If one fallopian tube was injured or removed, an egg can be fertilized in the other tube before entering the uterus.

If both fallopian tubes were injured or removed, in vitro fertilization might be an option. With this procedure, mature eggs are fertilized in a lab and then implanted into the uterus.

If you choose to conceive again, seek your doctor's advice. Early blood tests and ultrasound imaging can offer prompt detection of another ectopic pregnancy — or reassurance that the pregnancy is developing normally.

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